1. Field of the Invention
This invention relates to endoscope devices and more particularly to an endoscope device removably fitted in a tip portion of an endoscope inserting portion with an attachment for changing a view angle and visual field direction or protecting the tip portion and others.
2. Related Art Statement
There is recently extensively used a (medical) endoscope whereby an elongated inserting portion can be inserted into a body cavity to observe the interior of the body cavity or any treating tool can be used for such treatment as therapy. Among such endoscopes, there is also an industrial endoscope which can be inserted into an instrument or piping to inspect or treat its interior. Among such endoscopes, there are a flexible endoscope wherein the inserting portion is flexible and a rigid endoscope wherein the inserting portion is rigid.
Now, an endoscope is inserted, for example, into a body cavity, an illuminating light is radiated toward an object position within the body cavity, a reflected light from the object forms an image with an objective lens and the image is transmitted to an eyepiece through image guide fibers or the like so that the object can be sighted and observed. Therefore, depending on the object to be observed, it may be necessary to change a view angle or visual field direction and to protect the tip portion of the inserting portion or the object.
Therefore, there is already known a device which can be removably fitted in a tip portion of an endoscope inserting portion with an attachment for changing a view angle and visual field direction or protecting the tip portion. An example of it is shown in FIG. 1.
In FIG. 1, the reference numeral 1 represents an inserting portion of an endoscope and 2 represents a tip portion of the endoscope inserting portion. An attachment 3 for changing a view angle and visual field direction or protecting the tip portion 2 can be removably fitted to this tip portion 2. This attachment 3 has a recess 4 in which the endoscope tip portion 2 is to be engaged in the rear part, that is, on the endoscope connecting side and has a female screw 5 provided on the inner peripheral wall of the recess 4. On the other hand, a tubular connecting member 7 having a male screw 6 provided to be screwed with the above mentioned female screw 5 is rotatably fitted on the outer periphery of the endoscope tip portion. The male screw 6 of the connecting member 7 and the female screw 5 of the attachment 3 are screwed with each other and the connecting member 7 is rotated to pull in and fix the attachment 3 with the screws.
Now, in this formation, as a means whereby the tubular connecting member 7 removably fitted to the above mentioned endoscope tip portion 2 to fix the attachmnet 3 is held by the tip portion 2 so as not to be pulled off and dropped, conventionally a groove 8 in the peripheral direction has been peripherally formed in the tip portion of the connecting member 7 to be fitted on the outer periphery of the tip portion 2 and a C-ring 9 has been fitted in this groove 8.
However, in the connecting member holding means using the above mentioned conventional C-ring, in order that the C-ring may not be removed by an external force when the attachment is not fitted, it is necessary to elevate the dimensional precision of the C-ring. That is to say, the C-ring is in a form so plastically deformable that, when it is deformed, a space catching on the groove will be reduced and the C-ring will be likely to be removed. Therefore, it is necessary to take special care in working and storing the parts of the C-rings and assembling the products.
Such endoscope devices of this kind are seen to be suggested in the gazettes of Japanese utility model publications Nos. 31210/1984 and 87704/1982. In the prior art examples, a connecting member is rotatably and nonremovably fitted to the tip portion of an endoscope and a screw provided on the connecting member and a screw of the attachment are screwed with each other to screw and fix this attachment into the end portion of the endoscope. In these prior art examples, as a means whereby the connecting means for fixing the attachment to the endoscope tip portion is held in the endoscope tip portion so as not to be removable, the outer peripheral diameter of the endoscope tip portion in front of this connecting member is made larger or a flange is formed.